The present invention relates to a vehicle occupant protection apparatus. In particular, the present invention relates to an air bag having a vent that can be selectively opened to discharge inflation fluid.
It is known to provide an air bag with a vent. The vent opens, or is uncovered, when the air bag inflates to help protect a vehicle occupant, to discharge inflation fluid from the inflated air bag. In some air bags, the vent may be selectively opened depending on sensed factors, for example, whether the occupant""s seat belt is buckled. U.S. Pat. No. 6,290,257 shows one such air bag. In other air bags, such as the one shown in U.S. Pat. No. 5,405,166, the vent is formed as two openings that are initially aligned so that the vent is initially open and then closes after the internal bag pressure reaches a predetermined amount.
The present invention relates to a vehicle occupant protection apparatus comprising an inflatable vehicle occupant protection device having a deflated condition and an inflated condition. The device has a vent panel defining a first vent opening for enabling flow of inflation fluid out of the device. The apparatus includes a vent strap having a second vent opening movable relative to the first vent opening. The vent strap has opposite ends that are fixed when the protection device is in the deflated condition. The vent strap has slack due to the length of the strap being greater than the distance between the locations where its opposite ends are fixed. One of the ends of the vent strap moves as the protection device is inflated to remove the slack and move the second vent opening relative to the first vent opening.